The present invention relates to a rolling guide apparatus, such as a linear guide apparatus or circular guide apparatus.
A rolling guide apparatus comprises a first slide member including a pair of wing portions opposed to each other and a second slide member capable of moving relatively to the first slide member. A plurality of rolling elements, such as balls, are held between the wing portions of the first slide member and the second slide member.
For example, a linear guide apparatus includes a carriage as an example of the first slide member and a rail as an example of the second slide member. The carriage can relatively move in the axial direction (longitudinal direction) of the rail. The carriage includes the pair of wing portions and a connecting portion that connects the wing portions. First raceway grooves are formed individually on the respective inner surfaces of the wing portions. Second raceway grooves corresponding in position to the first raceway grooves are formed individually on the opposite side faces of the rail. Further, the carriage is formed having return ways that are continuous with the first raceway grooves, individually. The return ways and the first and second raceway grooves constitute an endless circulation way. The balls as the rolling elements are held in the circulation way.
In order to enhance the stiffness of the rolling guide apparatus described above, the rolling elements are held under a pre-load between the first and second slide members. Conventionally, the pre-load is adjusted by selecting the size of rolling elements. More specifically, a lot of types of rolling elements with different diameters-are prepared, and rolling elements with a suitable diameter are selected and incorporated into the rolling guide apparatus so that a desired pre-load is applied to the rolling elements. In general, the diameters of available rolling elements are graduated in micrometers.
Since the aforesaid conventional pre-load adjusting means involves preparation of a lot of types of rolling elements, its management takes much labor. Moreover, the range of dimensions of the available rolling elements is limited, so that the adjustable pre-load level is inevitably restricted.
Accordingly, the object of the present invention is to provide a rolling guide apparatus capable of easily adjusting a pre-load without being provided with many types of rolling elements with different diameters.
A rolling guide apparatus according to the present invention comprises: a first slide member including a pair of wing portions and a connecting portion connecting the wing portions and formed having first raceway grooves on the wing portions, individually; a second slide member combined with the first slide member, movable relatively to the first slide member, and formed having second raceway grooves corresponding in position to the first raceway grooves, individually; rolling elements held between the first and second raceway grooves; a residual compression stress region created on the surface region of the first slide member; and a worked portion formed on the residual compression stress region on an inner or outer surface of the connecting portion and capable of deforming the connecting portion as the residual compression stress region is worked and adjusting a pre-load on the rolling elements in accordance with the deformation.
According to this invention, the pre-load on the rolling elements can be adjusted to a desired value by simply forming the worked portion on the first slide member without preparing many types of rolling elements with different diameters that are required by conventional apparatuses.
Preferably, the process for forming the worked portion is carried out with the first and second slide members combined with each other. According to this invention, the pre-load can be adjusted without the trouble of disassembling or reassembling the first and second slide members.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.